The present disclosure relates to an image processing apparatus and method, an image processing system and a program. Specifically, the present disclosure relates to an image processing apparatus and method, image processing system and program that can easily realize calibration of multiple cameras, which take stereo images, at high accuracy in a small space.
In general, a technique that can take a three-dimensional image by the use of multiple cameras is common.
As a method of generating a three-dimensional image, there is known a general method of forming a stereo camera by setting up cameras of two different viewpoints, calculating the disparity based on stereo images taken by this stereo camera and generating a three-dimensional image by the use of this disparity.
By the way, although it is premised that the cameras of two different viewpoints used herein is set up in an appropriate direction, it is known that a certain physical gap is generated no matter how they are set up. Therefore, generally, by taking images formed with a chart pattern with respect to respective imaging directions of the cameras of two viewpoints and calculating correction parameters by calibration in advance using the imaging results, actual imaging results are corrected by these correction parameters and used.
As a calibration method of this stereo camera, projective transformation parameters are calculated by taking a plurality of images of a chart pattern on which multiple feature points whose position relationship is known are printed while changing viewpoints, and the calibration is realized (for example, see “A Flexible New Technique for Camera Calibration, http://research.microsoft.com/˜zhang”).
However, in this method, since the chart pattern is photographed several times in different viewpoints, it is requested to move the chart pattern or move the cameras, which increases the adjustment man-hour.
Therefore, as a method of performing calibration only by one imaging so as not to increase the adjustment man-hour in “A Flexible New Technique for Camera Calibration, http://research.microsoft.com/˜zhang,” there is suggested a method of overlapping two calibration chart patterns with permeability, photographing two or more chart patterns with different depths at the same time and calculating correction parameter (for example, see JP 2006-250889A).
However, in the techniques in both “A Flexible New Technique for Camera Calibration, http://research.microsoft.com/˜zhang” and JP 2006-250889A, when the gap angle of a camera (i.e., imaging area) with respect to the epipolar line (i.e., baseline) is estimated and corrected, it is requested to measure the geometrical position relationship of two or more feature points with different depths at the sub-pixel precision.
Therefore, there is suggested a technique that, by taking a texture image including a different depth from a plane chart pattern at the same time and minimizing the error amount of stereo matching of the right and left images, it is possible to easily and accurately correct the lilt of right and left camera imaging areas with respect to the baseline direction (=the epipolar line of the right and left cameras) of a correction target camera that fails to perform correction only by plane detection of one image (first depth) (for example, JP 2011-253376A).